1. Field of the Invention
This invention relates to conductor casings for oil and gas wells. More specifically, the invention is directed to a new and improved method and apparatus for remotely directing the deviation of the conductor casing of the well as it is being driven into the substratum.
2. Description of the Prior Art
It is commonly known that oil and gas wells are driven at varying slant angles for a variety of reasons. For example, in order to increase the lateral reach of the well, or in order to tap a deposit in a number of locations, the conductors have been driven at a slant, with respect to the vertical. In this procedure, the conductor casing joints generally remain uncurved; see U.S. Pat. No. 3,451,493, although it is known that the conductors have been precurved prior to their being driven into the substratum. Another known method describes the curving of pipe conductor during driving by forcing them through an arcuately arranged path of guide members affixed to the superstructure of the platform; see U.S. Pat. No. 3,670,507. This type of apparatus and method is generally deficient because it precludes versatility in drilling due to the fixed construction of the guide means on the platform, and in any event, the amount of curvature that can be obtained in the casing is predetermined by the preset guide means and may not be readily changed.
Due to the expense, difficulty and lack of flexibility of these methods, it may become desirable to drive the conductor pipe substantially vertically into the substratum and cause it to be deviated thereafter. In this regard, attention may be directed to pending U.S. application Ser. No. 035,635, wherein is shown a method and apparatus for perpendicular insertion and remote deviation of a conductor casing. This is accomplished by providing an articulating shoe or joint between two or more pipe joints. The shoe sections are held in alignment with the longitudinal axis of the conductor casing by shear pins. After the conductor casing has penetrated the ocean floor to the desired depth, the resistant forces resulting from the movement therein reach a level sufficient for the action of the driving hammer to shear the pins and force the articulated shoe to deviate from its alignment, thus altering the path of the conductor casing.
However, this method has limitations because the exact depth at which articulation occurs results from the nature of the substratum and other relatively uncontrollable factors, rather than at predetermined depth controlled by human operation. It is desirable, therefore, to design a means and method for actuating articulation at a predetermined depth, independent of the force of the hammer or the characteristics of the local substratum.